Internet

The Internet is a vast network of computers that allows users at various locations to share information and data and communicate with one another. The Internet is comprised of hundreds of millions of computers in more than 100 countries. It is not operated by any one business or government; it is a cooperative venture in which many companies, organizations, and individuals choose to participate by making their computers part of the network.

The Internet's beginnings are traced to a project called ARPAnet, which was begun in the 1960s by the US Department of Defense. Government and academic researchers collaborated to develop computer-to-computer communications using a new technology called packet switching. Packet switching is a means for chopping data into a series of data packets. Each packet is like a postcard with "to" and "from" labels. The packets are passed along by computers in the network until they reach their destination and are reassembled. Each packet can take a different path through the network to its destination, bypassing areas that might be damaged.

In 1972 the ARPAnet was demonstrated to the public at a computer conference. The response was enthusiastic, and other government agencies and academic institutions developed their own internal computer networks. These networks were seldom compatible with each other or with ARPAnet. In order for the ARPAnet to become a network of networks or an Internet, a universal format for transmitting data was required. The TCP/IP protocol (Transmission Control Protocol/Internet Protocol) was developed and implemented on the ARPAnet in 1983. The TCP/IP protocol allows different kinds of computers in different kinds of networks to communicate with each other. It ensures that packets are moved properly through the network and recovered if lost anywhere along the way.

Special computers called routers communicate with each other and figure out the best route for packets to take. Each computer connected to a TCP/IP network has a unique internet protocol (IP) address. This is a numerical address (such as 140.147.248.209) that other computers use to identify it. In 1984 domain names were introduced to make the network more user-friendly. A domain name (like uscongress.gov) is the word equivalent of an IP address. A network device called a DNS or domain name server converts domain names to IP addresses.

During the late 1980s the government began encouraging commercial involvement in its Internet to lower costs. The popularity of personal computers had spawned the formation of many local-area networks and increased demand for wide-area networks like the Internet. Companies called internet service providers were formed to provide dial-up access to private companies and citizens. In 1990 the original ARPAnet was decommissioned, and the public Internet grew rapidly as a tool for communications and commerce.

Early Internet users could send text messages to each other and store files so that other people could access them, but the process was complicated and required knowledge of computer languages. In 1989 Tim Berners-Lee proposed a new way to interface with the Internet called the World Wide Web. This interface used elements of a markup language called SGML (Standard Generalized Markup Language) to format information and include hypertext links between documents, even if they were stored on different computers.

The Internet was never designed to operate only one application or kind of software. E-mail (electronic mail) was developed in the early 1970s and went on to become one of the most popular applications. Other applications that are widely used include file transfer, real-time broadcasting and communications (including chat rooms), electronic bulletin boards, newsgroups, and Telnet. Each of these applications has a protocol that allows it take place. The World Wide Web makes all of these applications accessible through one interface.

Accessing the Internet from a personal computer requires a means for connection and software through which to communicate. Connection is via phone lines, cable, radio waves, or satellite to a special-purpose computer called a server or host system. These powerful computers, which are usually operated by internet service providers, are in communication with each other throughout the network and provide the backbone of the Internet infrastructure.

Although the Internet is not operated or managed by any one organization, there are several private groups that guide its development. The Internet Society provides some formal coordination of Internet technologies and applications. The non-profit organization includes thousands of member companies, governments, and individuals throughout the world. It also provides administrative support to the Internet Engineering Task Force and the Internet Architectural Board, groups which develop technical standards for Internet infrastructure. The Internet Corporation for Assigned Names and Numbers (ICANN) is recognized worldwide as the organization with authority to coordinate the allocation of IP address space, assign protocol parameters, and manage the domain name and root server systems. However, no organization controls who connects to the Internet or what types of information can be shared on it.

The ARPAnet developers shared their research and ideas with each other by posting documents called Request For Comments (RFC) on their computer network. These documents, which discussed protocol specifications and other technical issues, were accessible to all researchers. This free and open dissemination of information about the Internet continues today. Thousands of RFCs, including the first one written in 1969, are archived by the Internet Society at http://www.rfc-editor.org. The collection is updated daily as the Internet continues to evolve. These RFCs provide a written history and an ongoing description of the technical development of the Internet.